Halogen lamps containing methyl bromide or methylene chloride

ABSTRACT

A lamp exhibiting a long life characteristic includes in a bulb a mixture of methyl bromide and methylene chloride, the amount of methyl bromide and methylene chloride being respectively within the range of 0.03 to 0.55 Mu mol and 0.02 to 0.25 Mu mol per cc of the volume of the bulb.

United States Patent Sugano et al.

[ 1 March 6, 1973 HALOGEN LAMPS CONTAINING METHYL BROMIDE OR METHYLENE CHLORIDE Inventors: Keiichi Sugano; Yooji Yuge, both of Yokohama, Japan Tokyo Shibaura Electric Co., Ltd., Kawasaki-shi, Japan Filedl Aug. 4, 1971 Appl. No.: 168,872

Related U.S. Application Data Continuation-impart of Ser. No. 868,881, Oct. 23, 1969, abandoned.

Assignee:

U.S. Cl. ..313/222, 313/174, 313/223 Int. Cl. ..H01k 1/50 Field of Search ..313/222, 223, 174

[56] References Cited UNITED STATES PATENTS 3,586,896 6/1971 Meijer et a1. ..313/222 X 3,022,439 2/1962 Cooper, Jr. et a1 ..313/222 3,418,512 12/1968 T'Jampens et al ..313/222 X 3,453,476 7/1969 English ..313/222 X 3,484,146 12/1969 Meijer et a]. ..313/222 X 3,538,373 11/1970 Van Der Linden et al. ..313/222 X Primary Examiner-Palmer C. Demeo Attorney-George B. Oujevolk [57] ABSTRACT A lamp exhibiting a long life characteristic includes in a bulb a mixture of methyl bromide and methylene chloride, the amount of methyl bromide and methylene chloride being respectively within the range of 0.03 to 0.55 ,u.mol and 0.02 to 0.25 p.mol per cc of the volume of the bulb.

2 Claims, 2 Drawing Figures PATENTED R 975 V. Y Z.

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MIXING RATIO OF METHYL BROMIDE AND METHYLENE CHLORIDE (TT'IOI RATIO) HALOGEN LAMPS CONTAINING METHYL BROMIDE OR METHYLENE CHLORIDE CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of U.S. Pat. Application Ser. No. 868,881, filed Oct. 23, 1969, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to lamps and particularly to a halogen lamp in which an organic halogen compound is sealed.

A halogen lamp is, in general, known to have good luminescent efficiency, good color rendering and good operating property. Particularly, a lamp using an organic halogen, such as methyl bromide or methylene chloride is easy to handle and hence is used more commonly than a lamp in which an inorganic halogen is sealed. In each instance, however, the lamp is subject to the troublesome and difficult manufacturing technique that the amount of incorporation of halogen must be exactly controlled to a predetermined value. For example, a less amount of incorporation of halogen tends to result in blackening in a short time, while a slightly excess amount of incorporation results in etching of a low temperature region (usually lead-in parts and anchor parts adjacent to a filament) of the bulb. It will thus be seen that a slight variation in the amount of halogen to be sealed causes a blackening or etching, thereby shortening the operating life of the lamp and causing lamps to be unstable in duration from each other.

SUMMARY OF THE INVENTION The invention thus provides a halogen lamp, having a long life duration such as over several hundred hours, in which methyl bromide and methylene chloride are sealed in the bulb together with an inert gas the amount of methyl bromide and methylene chloride being respectively within the range of 0.03 to 0.05 p.mol per cc and 0.02 to 0.25 mol per cc of the volume of the bulb. According to the invention, it is possible to obtain lamps having a long duration and a less variation in duration in each lamp, and which is free from a blackening with a relatively small amount of the sealant.

A halogen lamp using a mixture of methyl bromide and methylene chloride as this application is already known by the U.S. Pat. No. 3,484,146. This known patent concerns a halogen lamp exhibiting a short life time, for example, about 30 hours, and does not describe the mixing ratio of methyl bromide with methylene chloride and the volume of them.

BRIEF EXPLANATION OF THE DRAWING FIG. 1 is a perspective view of the halogen lamp embodying this invention; and

FIG. 2 is a typical distribution diagram in the mixing ratio v., the charge of methyl bromide and methylene chloride to show the life of the lamp.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a transparent glass bulb encloses a coiled tungsten filament 11 of small diameter, for example, 0.15 to 0.25 mm, which in the prior art was believed to cause damage by etching, supported by anchors 12 at a plurality of portions in such a manner that the filament 11 extends in the direction of the longitudinal axis of the bulb 10. At both ends of the bulb pinched press portions 13 are formed in which molybdenum leaves 14 are hermetically embedded. Each leaf 14 is connected to a conductor 15 connected to each end of the filament 11 and is further connected to an outer conductor 16 which extends outwardly of the bulb. Within the tube a gaseous atmosphere is sealed consisting of a halogenated hydrocarbon formed of a mixture of methyl bromide and methylene chloride, and a suitable amount of an inert gas, such as argon introduced at a pressure of 600 to 700 mm Hg. The amounts of methyl bromide and methylene chloride are respectively within the range of 0.03 to 0.05 pmol and 0.02 to 0.25 [Ll'llOl per cc of the volume of the bulb. The inert gas may be replaced by a nitrogen gas, or both may be used together. In the latter case, it is desired that an inert gas such as argon be used in an amount of more than percent on the basis of the total weight.

It has been observed that the halogen lamp of the foregoing construction exhibits, when operated at a rated voltage of V and a rated wattage of 330 W, a lighting condition of high efficiency with its outer wall temperature teaching as far as above 250C during the lighting operation, and a long duration of more than 400 hours, without causing blackening and etching, and that the amount of incorporation of the total halogen components are less than that of a single sealant of halogenated hydrocarbon as used in a conventional device. Use of the halogenated hydrocarbon mixture as above described is also advantageous since the harmful effect on human bodies of methyl bromide can be reduced by the presence of methylene chloride.

In the halogen lamp described above, various parameters, such as the size of the bulb, the shape of the filament, and the electric current used, may be determined to permit the halogen lamp to have an outer wall temperature which should reach at least above 250C during its lighting operation, and at least one gas of the group consisting of nitrogen gas and an inert gas, such as neon, argon or xenon may be used together with said mixture.

It has been observed from the various tests that relatively good effects are obtained when methyl bromide and methylene chloride are mixedly sealed to be within the range of 0.03 to 0.55 umol and 0.02 to 0.25 umol per cc of the volume of the bulb, i.e. defined by lines a in FIG. 2.

Especially the best result has been obtained when the amounts of bromine, chlorine and hydrogen are respectively sealed to be 0.05 X 10 to 0.10 X 10" gramatom, 0.10 X 10" to 0.33 X 10' gram-atom, and 0.10 X 10" to 0.70 X 10' gram-atom, all per cc of the volume of the bulb, i.e. methyl bromide and methylene chloride are mixed within the range defined by lines b in FIG. 2.

FIG. 2 shows results of experiments which illustrate various advantages of the invention, the ordinate representing the amount of incorporation (pmol) of methyl bromide and methylene chloride per cc of the bulb, and the abscissa representing in mol ratio the mixing ratio of said methyl bromide and methylene chloride. The experiments have been carried out by measuring the duration of each of a number of halogen lamps having a varied mixing ratio and amount of incorporation of methyl bromide and methylene chloride.

There are shown in the following table the measurements of the experiments (A to Z). It may be noted 5 from FIG. 2 plotting the measurements that a life time is more than 400 hours in the area enclosed by lines a and especially more than 1,000 hours in that surrounded by lines b.

TABLE A B C D E TOTAL 0.32 0.32 0.23 0.15 0.13

X10 mol CH,Br-.CH,C1 1.67:1.0 1.0:2.2 1.01109 1.0115 1.0:1.17

(molratio) Life Time 883 910 1250 1634 2128 (hour) L M N O P Q R S T U V W 0.80 0.66 0.4 0.1 0.1 0.9 9021.0 0.911.] 1.1239 0.3217 0.1:1.9 3.0110 403 560 631 622 240 210 X Y Z 0.85 0.85 0.54 0.7:1.3 1.0:9.0 0.2:2.3 279 284 361 What we claim is:

1. A halogen lamp comprising a bulb, a tungsten filament accommodated in the bulb, at least one gas selected from the group consisting of nitrogen gas and inert gas sealed in the bulb, and a mixture consisting of methyl bromide and methylene chloride, the amounts of methyl bromide and methylene chloride being respectively within the range of 0.03 to 0.55 umol per cc and 0.02 to 0.25 umol per cc of the volume of the bulb.

2. The halogen lamp according to claim 1 wherein the amounts of methyl bromide and methylene chloride are respectively within the range of 0.05 to 0.10 pmol and 0.05 to 0.165 p.mol per cc of the volume of the bulb. 

1. A halogen lamp comprising a bulb, a tungsten filament accommodated in the bulb, at least one gas selected from the group consisting of nitrogen gas and inert gas sealed in the bulb, and a mixture consisting of methyl bromide and methylene chloride, the amounts of methyl bromide and methylene chloride being respectively within the range of 0.03 to 0.55 Mu mol per cc and 0.02 to 0.25 Mu mol per cc of the volume of the bulb. 